When fingernails and toenails of adults and children become weak and imbrittled, a variety of treatment can be employed to strengthen and harden such nails. Since water soluble fluorides have been used for many years to harden human teeth and since nail tissues are similar in certain respects to teeth tissue, attempts have been made to utilize water soluble flourides in treating fingernails and toenails to strengthen and harden them.
U.S. Pat. No. 4,919,920 discloses a composition for use in strengthening and hardening nails which takes the form of an aqueous vehicle having dissolved therein a keratin hardening and strengthening agent containing an effective amount of fluoride ion, the composition having a pH of 3.8 to 8. This patent further discloses a method for using this composition wherein it is formed into a cream which used to coat the surface of the nail to be treated. The coating is left in contact with the surface of the nail for at least one minute and usually for a longer period. Thereafter, the excess of the coating is removed. The method must be repeated at least once daily until the desired hardness and strength is obtained. All nail polish must be removed before treatment since the cream cannot penetrate polish. Moreover, the nail must be carefully dried after the excess cream has been removed because the polish will not otherwise adhere to the nail.
Moreover, the fluoride ion used in this composition can hydrolyze and form hydrofluoric acid which, if not washed off as instructed can etch or mottle the nail and damage the nail surface.
The present invention is directed toward both a new composition and a new method using ammonium hexafluoride phosphate in an organic vehicle which is not subject to and overcomes the disadvantages of the known composition and method discussed above.